The Electron Paramagnetic Resonance (EPR) investigations made on technetium compounds (99Tc) are reviewed. Different measuring modes are used: liquid solution, frozen solution, diamagnetically diluted powders and single-crystals. Also double resonance and pulse techniques are applied. The spectra obtained are discussed according to the oxidation state or the metal, the cordination geometry and the bonding properties of the complex molecules. Further on, it is shown that EPR is a suitable method for monitoring chemical reactions in which Tc2+or Tc6+compounds are involved.